Ascorbate (L-Ascorbic acid or Vitamin C) is a six-carbon lactone that is synthesized from glucose in the liver of most mammalian species, but not by humans. Therefore, humans must obtain ascorbate in their diet in order to survive. In humans, ascorbate acts as an electron donor for eight different enzymes. It also serves as an antioxidant and may be beneficial for reducing the risk of developing chronic diseases such as cancer, cardiovascular disease, and cataracts. Cayman’s Ascorbate Assay provides a reproducible, sensitive fluorescence-based tool for quantifying ascorbate from plasma, serum, urine, and fruit juices.